High Temperature Wirebond Power Module
As shown in Fig.1, in the prototype multi-chip phase-leg module, two groups of three JFETs were paralleled in top-leg and bottom-leg. The layout was designed by considering the reduction of parasitic parameters and the balance of the paralleled devices. Based on the SiC wirebond packaging, materials for each part of the module are compared and selected to ensure the full package can function reliably at 250°C. The promising results of thermal cycling test on die-attachment and wirebond assemblies prove that the proposed package can perform well for large temperature excursion. The multi-chip phase-leg power module following the layout design was fabricated, as shown in Fig.1. This prototype power module was operated with 700 V input voltage, 5A input current and the power rating of 3.5 kW at the estimated junction temperature of 250°C. The switching waveforms of top JFET gate signal, bottom JFET gate signal, top JFET drain to source voltage and inductor current are shown in Fig.2. The continuous power test lasted 20 minutes after the system was running in the steady state. The test results prove that the designed wirebond package can support the SiC multi-chip power module operating at 250°C junction temperature.
By taking advantage of the CPES high temperature planar packaging, SiC devices are well suited for operation in harsh temperature environments like aerospace and automotive applications.